"Mutant" rodents can grow to 5 kg, are about as big as cats, outnumber residents 6-to-1

According to a top government-owned English language newspaper in the United Arab Emirates -- The National -- the streets of Tehran have been running red with blood, as the government has deployed military troops to kill mutant rodents.

While Iran's Revolutionary Guard is typically more focused on hurling threats against its western adversaries, it's been forced to focus on the homeland amidst chaos in Tehran. The city has been plagued by an insidious infestation of an unusual breed of rats, which reportedly grow to the size of a cat.

Mohammad Hadi Heydarzadeh, the head of Tehran municipality's environmental agency told a state TV news agency last month, "It's become a 24/7 war. We use chemical poisons to kill the rats during the day and the snipers at night."

So far 2,000 of the fearsome creatures have been killed.

The problem has become exacerbated as snow from the Alborz mountains seasonally melts, raising water levels and flushing the rats out of their subterranean lairs. Researchers estimate the rats may outnumber their human adversaries six to one. And these aren't your run-of-the-mill rodents. Reportedly they grow to around 5 kg (11 lbs).

Ismail Kahram, an environmental adviser to the city council, says the rats have changed in appearance over the years. He comments, "They seem to have had a genetic mutation. They are bigger now and look different. These are changes that normally take millions of years of evolution."

U.S. experts say this is unlikely, pointing out that even common black rats can get quite large. Dr. David Baker, a laboratory animal veterinarian at LSUtells the Huffington Post, "Nearly all genetic mutations identified across the field of biology are harmful and confer a disadvantage to the species rather than an advantage. It’s not like in the sci-fi movies. [But] during the Middle Ages, [standard] black rats in Europe reportedly grew large enough -- and children were small enough -- to carry off babies. Those had to have been some big rats."

Regardless of who is right, one thing is for sure -- these are some big rats.

One of Iran's massive "mutant" rats. [Image Source: Reuters]

The city uses tons of poison a year. The special toxin used causes the rodents to become very thirst before death, a blessing as they then go off to die in the sewers, limiting the public health risk. Still, it appears that the city is making little headway against the ever growing rodent threat.